Rotating machine speed estimation

Abstract

Embodiments of a process for estimating a rotational speed of a rotating component and a process for estimating an acceptable rotor imbalance of a rotating component are provided herein. The process for estimating the rotational speed of a rotating component for a charging system comprises measuring a vibration signal of the rotating component by means of a sensor; and identifying harmonic train members from a plurality of peaked components of the vibration signal. Further, the process comprises determining a candidate fundamental frequency from the harmonic train members; and determining a derived vibration amplitude value from the vibration signal. This determination involves a filtering of the vibration signal, removing periodic contributions having a high amplitude. A scalar value is then derived from the filtered signal as a derived vibration amplitude value, representing the integrated total vibration amplitude of the filtered signal at the current speed. The process comprises verifying a consistency condition between the derived vibration amplitude value and the candidate fundamental frequency using a predetermined speed-amplitude map, associating speed values with their respective derived vibration amplitude values. For determining an acceptable rotor imbalance, a speed-amplitude map obtained at a time when the imbalance is acceptable is compared to a speed-amplitude map at a later point in time. An offset between the maps may indicate an inacceptable imbalance.

The invention claimed is: 
     
       1. A process for estimating a rotational speed of a rotating component for a charging system, the process comprising:
 measuring a vibration signal of the rotating component by means of a sensor; 
 identifying harmonic train members from a plurality of peaked components of the vibration signal; and determining a candidate fundamental frequency from the harmonic train members; 
 determining a derived vibration amplitude value from the vibration signal; 
 wherein the step of determining the derived vibration amplitude value comprises filtering the vibration signal by removing the highest amplitude signals to the vibration signal and determining a total vibration amplitude of the filtered vibration signal; and 
 verifying a consistency condition between the derived vibration amplitude value and the candidate fundamental frequency using a predetermined speed-amplitude map, 
 wherein the total vibration amplitude is based on the root-sum-square of the filtered vibration signal, or the total vibration amplitude is based on the root-mean-square of the filtered vibration signal, and 
 wherein the rotating component is a rotating component of a turbocharging system and/or a turbocompound. 
 
     
     
       2. The process according to  claim 1 , wherein verifying the consistency condition comprises:
 determining an expected rotational speed for the derived vibration amplitude value from the speed-amplitude map to verify whether the candidate fundamental frequency corresponds to the rotational speed. 
 
     
     
       3. The process according to  claim 2 , wherein:
 if the candidate fundamental frequency is substantially equal to the expected rotational speed, the rotational speed is determined to correspond to the candidate fundamental frequency; or else if; 
 if the candidate fundamental frequency is substantially equal to an integer fraction or an integer multiple of the expected rotational speed, the rotational speed is determined to correspond to the candidate fundamental frequency divided by the integer fraction or the integer multiple ratio; or else if; 
 if the candidate fundamental frequency is not substantially equal to the expected rotational speed and not substantially equal to an integer fraction or an integer multiple of the expected rotational speed, the rotational speed is determined to correspond to the expected rotational speed. 
 
     
     
       4. The process according to  claim 1 , further comprising establishing of the predetermined speed-amplitude map by:
 operating the rotating component at a plurality of rotational speeds; and 
 determining respective derived vibration amplitude values for each of the rotational speeds; and 
 establishing a speed-amplitude table comprising the rotational speeds and the respective derived vibration amplitude values. 
 
     
     
       5. The process according to  claim 4 , wherein determining the speed-amplitude map includes:
 determining a speed-amplitude map function based on entries in the speed-amplitude table. 
 
     
     
       6. The process according to  claim 1 , further comprising the step:
 updating the speed-amplitude map with the estimated rotational speed and the respective derived vibration amplitude value. 
 
     
     
       7. The process according to  claim 1 , wherein the filtering of the vibration signal includes:
 removing at least 10% of signals having a highest amplitude of a power spectrum of the vibration signal. 
 
     
     
       8. The process according to  claim 1 , wherein the process is an online process. 
     
     
       9. The process according to  claim 1 , where in the step of extracting harmonic train members comprises:
 identifying peaked components in the vibration signal and determining a frequency of each of the peaked components; and 
 extracting harmonic train members from the plurality of peaked components, the frequencies of each harmonic train member being substantially integer fractions or substantially integer multiples of at least one other member of the harmonic train members. 
 
     
     
       10. A process for estimating an acceptable rotor imbalance of a rotating component, the process comprising the steps:
 operating the rotating component at a first plurality of rotational speeds and measuring a first plurality of vibration signals of the rotating component; 
 determining a derived vibration amplitude value for each of the first plurality of rotational speeds; 
 wherein the step of determining the derived vibration amplitude value comprises filtering the first plurality of vibration signals by removing the highest amplitude signals to the vibration signal and determining a total vibration amplitude of the filtered vibration signal of the first plurality of vibration signals; 
 establishing a first speed-amplitude map; and subsequently: 
 operating the rotating component at a second plurality of rotational speeds and measuring a second plurality of vibration signals of the rotating component; 
 determining a derived vibration amplitude value for each of the second plurality of rotational speeds; 
 wherein the step of determining the derived vibration amplitude value comprises filtering the second plurality of vibration signals by removing high amplitude signals to the vibration signal and determining a total vibration amplitude of the filtered vibration signal of the second plurality of vibration signals; 
 establishing a second speed-amplitude map; 
 estimating the rotor imbalance of the rotating component based on a comparison between the first speed-amplitude map and the second speed-amplitude map, 
 wherein the total vibration amplitude of the filtered vibration signal of the first plurality of vibration signals and/or of the filtered vibration signal of the second plurality of vibration signals is based on the root-sum-square of the filtered vibration signal spectrum, or the total vibration amplitude of the filtered vibration signal of the first plurality of vibration signals and/or of the filtered vibration signal of the second plurality of vibration signals is based on the root-mean-square of the filtered vibration signal of the first plurality of vibration signals and/or of the filtered vibration signal of the second plurality of vibration signals, and 
 wherein the rotating component is a rotating component of a turbocharging system and/or a turbocompound. 
 
     
     
       11. The process according to  claim 10 , further comprising:
 establishing the first speed-amplitude map by:
 establishing a first speed-amplitude table comprising the first plurality of rotational speeds and the respective derived vibration amplitude values; 
 determining a first speed-amplitude map function based on entries in the first speed-amplitude table; 
 
 establishing the second speed-amplitude map by:
 establishing a second speed-amplitude table comprising the second plurality of rotational speeds and the respective derived vibration amplitude values; 
 determining a second speed-amplitude map function based on entries in the second speed-amplitude table; and 
 
 estimating an imbalance of the rotating component based on a shift between the first speed-amplitude map and the second speed-amplitude map. 
 
     
     
       12. The process according to  claim 1 , wherein predetermining the speed-amplitude map and/or determining the speed-amplitude map function is carried out online. 
     
     
       13. The process according to  claim 11 , further comprising estimating an imbalance of the rotating component based on a rotational speed offset or a derived amplitude offset between the first speed-amplitude map function and the second speed-amplitude map function.